Method and apparatus for network congestion control

Abstract

The present invention is a delay based model and in fact uses queuing delay as a congestion measure, providing advantages over prior art loss based systems. One advantage is that queuing delay can be more accurately estimated than loss probability. This is because packet losses in networks with large bandwidth-delay product are rare events under TCP Reno and its variants (probability on the order 10−7 or smaller), and because loss samples provide coarser information than queuing delay samples. Indeed, measurements of delay are noisy, just as those of loss probability. Thus, another advantage of the present invention is that each measurement of queuing delay provides multi-bit information while each measurement of packet loss (whether a packet is lost) provides only one bit of information for the filtering of noise. This makes it easier for an equation-based implementation to stabilize a network into a steady state with a target fairness and high utilization. In addition, the dynamics of queuing delay provides scaling with respect to network capacity. This helps maintain stability as a network scales up in capacity.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the benefit of priority from pending U.S. Provisional Application No. 60 / 477,830 filed Jun. 12, 2003, U.S. Provisional Application No. 60 / 479,251 filed Jun. 16, 2003, and U.S. Provisional Application Ser. No. 60 / 482,060 filed Jun. 23, 2003, which are herein incorporated by reference in their entirety.GOVERNMENT LICENSE RIGHTS[0002]The U.S. Government has certain rights in the present invention pursuant to Grant Nos. ANI-0113425 and ANI-0230967 awarded by the National Science Foundation.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]The present invention relates to the field of networks and to methods and apparatus for congestion control.[0005]Portions of the disclosure of this patent document contain material that are subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in t...

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Benefits of technology

[0063]The present invention provides a method and apparatus for network congestion control. The present invention is a delay based model and in fact uses queuing delay as a congestion measure, providing advantages over prior art loss based systems. One advantage is that queuing delay can be more accurately estimated than loss probability. This is because packet losses in networks with large bandwidth-delay product are rare events under TCP Reno and its variants (probability on the order 10−7 or smaller), and because loss samples provide coarser information than queuing delay samples. Indeed, measurements of delay are noisy, just as those of loss probability. Thus, another advantage of the present invention is that each measurement of queuing delay provides multi-bit information while each measurement of packet loss (whether a packet is lost) provides only one bit of information for the filtering of noise. This makes it easier for an equation-based implementation to stabilize a network into a steady state with a target fairness and high utilization. In addition, the dynamics of queuing delay provides scaling with respect to network capacity. This helps maintain stability as a network scales up in capacity.

is that each measurement of queuing delay provides multi-bit information while each measurement of packet loss (whether a packet is lost) provides only one bit of information for the filtering of noise. This makes it easier for an equation-based implementation to stabilize a network into a steady state with a target fairness and high utilization. In addition, the dynamics of queuing delay provides scaling with respect to network capacity. This helps maintain stability as a network scales up in capacity.

Problems solved by technology

Indeed, measurements of delay are noisy, just as those of loss probability.

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